[vbox-dev] IDisplay in IConsole::display is empty

[Karoline Haus]

Hi

I'm building a VBox Frontend graphics driver working similar to VBoxSDL.

When I try to start the VM and get the IDisplay pointer using


gConsole->COMGETTER(Display)(gDisplay.asOutParam());

then gDisplay is always NULL. In what cases can this happen? I have no idea how to debug the problem.

Any pointers would be really appreciated.

Thanks,
Karoline
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[Klaus Espenlaub]

Hi Karoline,

Post by Karoline Haus
Hi
I'm building a VBox Frontend graphics driver working similar to VBoxSDL.
When I try to start the VM and get the IDisplay pointer using
gConsole->COMGETTER(Display)(gDisplay.asOutParam());
then gDisplay is always NULL. In what cases can this happen? I have no
idea how to debug the problem.

This sounds like the type of the session lock you're requesting is
incorrect. For some time now (since 4.2) we have split out a special
lock type for VM processes, and only those will get the objects below
the console initialized. This greatly lowers the cost for "normal API
client" sessions, which are used e.g. by VBoxManage and the VM manager
GUI, as they never needed these objects.

So double check if you use LockType_VM - all VM frontends do this since
the split happened (and the API change is documented in the SDK manual),
see VBoxSDL.cpp.

Hope this helps,
Klaus

Post by Karoline Haus
Any pointers would be really appreciated.
Thanks,
Karoline

[Karoline Haus]

Klaus Espenlaub <klaus.espenlaub at oracle.com> schrieb am 15:22 Freitag, 24.Januar 2014:

Hi Karoline,

Post by Karoline Haus
Hi
I'm building a VBox Frontend graphics driver working similar to VBoxSDL.
When I try to start the VM and get the IDisplay pointer using
gConsole->COMGETTER(Display)(gDisplay.asOutParam());
then gDisplay is always NULL. In what cases can this happen? I have no
idea how to debug the problem.

This sounds like the type of the session lock you're requesting is
incorrect. For some time now (since 4.2) we have split out a special
lock type for VM processes, and only those will get the objects below
the console initialized. This greatly lowers the cost for "normal API
client" sessions, which are used e.g. by VBoxManage and the VM manager
GUI, as they never needed these objects.

So double check if you use LockType_VM - all VM frontends do this since
the split happened (and the API change is documented in the SDK manual),
see VBoxSDL.cpp.

Hope this helps,
Klaus

Post by Karoline Haus
Any pointers would be really appreciated.
Thanks,
Karoline

You were right - that was the problem!!! Thanks!

Karoline
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